BEIRUT — Hezbollah, the Lebanese Shiite political and militant group, has ramped up its support for the Syrian government, sending in military advisers to aid in the bloody struggle against the opposition, U.S. and Lebanese government officials say.

Hezbollah’s involvement is a clear indication that the uprising, now a year and a half old, is drawing in Syria’s neighbor and broadening a conflict that has the potential to destabilize the entire region. It also marks a worrying turn for the Syrian rebels, who already face one of the region’s most potent armies and now must contend as well with a disciplined and sophisticated militia.

The U.S. government this month accused Hezbollah of providing aid to the Syrian government, an allegation the group has denied. Any acknowledgment that it is sending help to the regime of President Bashar al-Assad risks worsening tensions in Lebanon between Hezbollah and Lebanese Sunnis who support the mostly Sunni opposition in Syria.

But Lebanese officials say the support is becoming harder to hide and has markedly increased since a July 18 bomb attack in Damascus that killed four senior security officials, including Assef Shawkat, Assad’s brother-in-law.

Lebanese officials and analysts say Hezbollah militants are now fighting — and dying — in the conflict, although U.S. officials have not confirmed the group’s combat role. The Lebanese officials cite as evidence quiet burials in Hezbollah-dominated areas of Lebanon, with the families of the “martyrs” warned not to discuss the circumstances of their sons’ deaths.

“Hezbollah has been active in supporting the Syrian regime with their own militia,” said a Lebanese government official allied with a political bloc opposed to Hezbollah who spoke on the condition of anonymity because of the issue’s sensitivity. “They’ve been quite involved in a combat role, quite involved in fighting.”

Hezbollah has a well-armed and trained militia that is considered the strongest fighting force in Lebanon. But the group also oversees a powerful political party and runs a number of organizations that provide social services to Shiite Muslims, its main supporters, throughout the country.

Recruitment efforts

In some villages in south Lebanon and the Bekaa Valley in the eastern part of the country, young men loyal to Hezbollah are recruiting volunteers to fight in Syria, according to Lebanese officials. And a number of secret funerals for young men killed in Syria have been held in Shiite strongholds.

This month, the U.S. Treasury Department announced sanctions against Hasan Nasrallah and two other Hezbollah leaders in connection with the group’s activities in Syria. The department accused Hezbollah of “providing training, advice, and extensive logistical support to the Government of Syria.” Hezbollah has also helped the Syrian government push rebel forces from some areas in Syria, the Treasury Department said.

Hezbollah’s heightened role in the conflict comes at the same time that Iran’s Revolutionary Guard Corps appears to be playing a bigger role in Syria. The Treasury Department said that the two groups are coordinating their military aid in Syria and that Hezbollah has helped the Revolutionary Guard train Syrian forces.

The conflict in Syria is dividing the region along sectarian lines, with the dominant Shiite powers, Iran and Hezbollah, backing the Alawite government of Assad. The Alawite faith is an offshoot of Shiism. Turkey, Saudi Arabia and Qatar, all countries with Sunni majorities, are backing the rebels, who are predominantly Sunni.

Asked about the role that both Hezbollah and the Iranian Revolutionary Guard are playing in the Syria conflict, a senior U.S. intelligence official said that both have expanded their presence and role in Syria in recent months. But the official, who spoke on condition of anonymity because of the sensitivity of the subject, said it appears that they have stopped short of carrying out operations or attacks.

Guerrilla warfare

Hezbollah’s involvement could signal a tougher fight ahead for the Syrian rebels. Hezbollah fighters, expert in guerrilla warfare, fought the Israeli military to a standstill in 2006 and could provide a useful complement to the Syrian military, which has experience in conventional warfare, perhaps providing insight into the rebels’ operations.

Hezbollah officials have denied any role in the conflict in recent months. A Hezbollah spokesman reached by phone in Beirut on Friday declined to comment on allegations that the group is involved in the Syria conflict.

Lebanese government officials say Hezbollah has become deeply involved and is trying to keep its activities under wraps. Dozens of Hezbollah fighters have been killed in Syria, according to a Lebanese government official who is a member of the political bloc opposed to Hezbollah.

The fighters who are killed in Syria do not receive the large public funerals that Hezbollah usually organizes for militants killed in clashes with the Israeli military. Instead, the “martyrs” are buried discreetly and families are urged not to talk about the circumstances of the death, three government officials said. All three of the officials are members of the political bloc opposed to Hezbollah.

A number of families have complained bitterly to Hezbollah about the deaths of their relatives and their secretive burial, one of these officials said. There is a debate within the Lebanese Shiite community about the Syrian conflict, even among Hezbollah supporters, and some say that the fight in Syria does not have the same prestige as the fight against the Israelis.

Obituaries for Hezbollah fighters have also started appearing in local newspapers such as al-Safir, one of these officials said, without the circumstances of the death being explained.

There has been one notable exception to these discreet burials, according to Lokman Slim, a political activist who runs Hayya Bina, a civic initiative that aims to make Lebanese politics less sectarian, and is a frequent critic of Hezbollah.

In early August, a senior Hezbollah military commander named Musa Ali Shehimi was killed in Syria, according to Slim, and a large funeral was held for him in Lebanon without specifying where or how he was killed. But the bodies of a handful of Hezbollah militants who were killed at the same time as Shehimi were returned to the families at different times, Slim says, in order to avoid unnecessary attention.

A news site that appears to be run by Hezbollah supporters, al-Intiqad, ran an item about Shehimi’s funeral on Aug. 10 along with an alleged picture of the funeral. A handful of Hezbollah commandos are shown carrying a coffin draped in the Hezbollah flag in the photo with hundreds of people packed in the street behind them. The article notes that Shehimi “died while performing his jihadi duty” without giving any further details.

The funeral was attended by Hezbollah parliamentarians Ali Fayyad and Ali Ammar, the article said, and Shehimi was buried in the “Garden of Martyrs” cemetery in Beirut, the same location where the group’s top military commander, Imad Mughniyah, who was assassinated mysteriously in Damascus in 2008, is reportedly buried.

“Only this Shehimi was given a measure of a public funeral,” Slim said. “There’s a whole machine of how they’re administering these deaths.”

Propaganda efforts

Hezbollah is also helping the Syrian government with its news and propaganda, Slim said. Communication specialists from Hezbollah’s TV station al-Manar are helping Syria’s official channel al-Ikhbariya present slick news packages with the government’s viewpoint.

More worrying for some Lebanese are reports that Hezbollah is targeting Syrian opposition members near the border areas inside Lebanese territory. These reports could inflame sectarian tensions with Lebanese Sunnis.

A clash between Syrian rebels and Hezbollah fighters inside Lebanese territory at the beginning of the summer left two Hezbollah fighters dead, according to a Lebanese former senior security official.

But Hezbollah is trying to keep the peace at home, many observers say. The group has little interest in spreading sectarian strife inside Lebanon or destabilizing the government in which they play a key role.

“Hezbollah doesn’t want to pick a fight inside Lebanon,” said Paul Salem, the head of the Carnegie Middle East Center in Beirut.

Greg Miller in Washington and Suzan Haidamous in Beirut contributed to this report.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.

To pause and restart automatic updates, click "Live" or "Paused". If paused, you'll be notified of the number of additional comments that have come in.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.